Better messaging when connecting to 1.2 device or when connection times out

[digitarald]

With App Manager required for 1.2, devs still use Simulator and try to push to 1.2 devices. To avoid this confusion and people giving up, the messaging could be improved.

If we can detect that a 1.2 device got connected; we should warn the user. If we know that connection times out for 1.2 devices; we can add a note to the message that he might be trying to push to a 1.2 device and should use App Manager.

Thoughts?

[brendandahl]

Also discussing in https://bugzilla.mozilla.org/show_bug.cgi?id=935715